Cams for trials

[dave Grose]

I am building a new 2 ltr Fiat 132 engine to fit in my Marlin that i classic trial . I need a low torque engine any advise on cams & suppliers

Dave

[Guy Croft]

I need the whole engine spec/ancillaries (like fuel system, exhaust) and the working powerband please.

Make it detailed but concise, use bullet points rather than pragraphs.

Your input will pretty well determine the usefulness of my advice. If you're not sure how to spec the motor just ask.

GC

[dave Grose]

The carb is a Weber 40DCNF with a K&N filter fitted on a standard manifold by previous owner. I have the standard Weber if this is better.

The head has been ported as per the instructions on your old web site. No other work done on head. The exhaust is the standard exhaust manifold as a 4 branch would need to be made to order as space is confined

The rest of the engine is std bore size etc., as all the bottom end was in good order. What other specification info do you require & where do I find it?

I have enough power in my existing 1600 - but it is in the wrong end of the rev band.

Dave

[Guy Croft]

If you want bottom-end torque, that is idle to say 5000 (maybe higher) then the standard cam setup is best, and a single carb.

The only alteration beyond that which you have already done (modified head) is bigger inlet valves (costly) and higher compression ratio. Those two things are the only ones (debarring bigger bore size/bigger capacity) that will give more bottom end torque.

Pistons for high compression will have to be forged and you would aim to try and get 10.5/1, bigger valves will make the job more difficult on that small engine, the combustion chamber is pretty roomy already..

The DCNF might be OK but is not really a rear-wheel drive carb, keeping the carb small is a good idea for bottom-end torque, but whethere the ancient OE carb is up to the job is very questionable. I'd maybe be looking for a new one from a Weber dealer from a Ford 1600 Pinto engine eg: Capri or similar.

GC